GAO reviewed Army, Navy, and Air Force integrated communication, navigation, and identification avionics (ICNIA) development programs to: (1) identify existing and future examples of integrated avionics systems and their expected costs and benefits; (2) determine whether existing integration programs are adequately emphasizing long-term efforts that will benefit future generations of military aircraft; and (3) determine whether existing development programs in the services should be merged. GAO found that the Air Force and the Army are jointly developing ICNIA technology. While the Navy recognizes the need for ICNIA technology for its future generations of aircraft, it has not joined the joint development effort because no funds are available, since no Navy aircraft program has specified a requirement for ICNIA technology, and it is concerned that it could become committed to specific hardware configurations before it can determine its specific requirements. GAO also found that ICNIA technology could: (1) reduce the size, weight, and cost of existing single-function avionics systems by up to 50 percent; (2) provide design flexibility to meet changing threats; (3) if standardized, decrease support costs significantly; and (4) enable aircraft to continue missions in the event that individual system components fail. GAO believes that: (1) the incremental cost to the Department of Defense of the Navy’s participation in the joint effort would be low compared to the cost of a separate Navy program; (2) the Navy could fund its participation in the joint effort by using research and development funds; and (3) joint development is more likely to succeed if the Navy participates in the early stages of the program.